EP0429843A1 - Buchse für hohe Gleichspannungen - Google Patents

Buchse für hohe Gleichspannungen Download PDF

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Publication number
EP0429843A1
EP0429843A1 EP19900120182 EP90120182A EP0429843A1 EP 0429843 A1 EP0429843 A1 EP 0429843A1 EP 19900120182 EP19900120182 EP 19900120182 EP 90120182 A EP90120182 A EP 90120182A EP 0429843 A1 EP0429843 A1 EP 0429843A1
Authority
EP
European Patent Office
Prior art keywords
bushing
condenser
condenser body
tube
conductor
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP19900120182
Other languages
English (en)
French (fr)
Other versions
EP0429843B1 (de
Inventor
Asa Hammarsten
Lennart Strandberg
Bengt-Olof Stenestam
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB AB
Original Assignee
Asea Brown Boveri AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
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Application filed by Asea Brown Boveri AB filed Critical Asea Brown Boveri AB
Publication of EP0429843A1 publication Critical patent/EP0429843A1/de
Application granted granted Critical
Publication of EP0429843B1 publication Critical patent/EP0429843B1/de
Anticipated expiration legal-status Critical
Revoked legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F27/00—Details of transformers or inductances, in general
    • H01F27/02—Casings
    • H01F27/04—Leading of conductors or axles through casings, e.g. for tap-changing arrangements

Definitions

  • the invention relates to a bushing for high direct voltages with a condenser body for field control of the connection between the bushing and a conductor connected to the bushing according to the precharacterising part of claim 1.
  • the bushing is particularly designed for transformers which are connected to convertors in HVDC plants.
  • a flashover will occur between the electro­des.
  • the flashover tendency may be minimized by inserting between the electrodes an insulator body which functions as a barrier.
  • Transformer bushings may comprise an upper insulator and a lower insulator of electric porcelain. At the joint between these there is a fixing flange which is connected to the transformer casing. In the centre of the bushing there is a tube on which is wound a condenser body to obtain a favou­rable electrical field distribution. The current can be con­ ducted through the tube or a flexible conductor drawn through the tube.
  • Condenser bodies for bushings are described in a number of patent specifications and publications of various kinds. In this connection, the following may, inter alia, be mentio­ned, namely EP-A-0 032 690 "Foil-insulated high voltage bushing with potential control”, EP-A-0 032 687 “High-vol­tage bushing with layers of embossed insulating foils”, EP-­A-0 051 715 "Safety device for high-voltage bushings", ASEA Journal 1981, Volume 54, No. 4, pages 79-84.
  • Common and ty­pical for the design of the condenser bodies is that they have a central circular-cylindrical portion. From both ends this portion changes into outwardly-directed straight fru­strums of cones whose cross section areas have a decreasing radius.
  • a variant of the design of a condenser body is disclosed in GB-B-1 025 686, "Pothead for connecting oil-filled cables to transformers and other electrical apparatus".
  • the condenser body has a conical part terminating towards the transformer.
  • the con­denser body terminates in a cross section area which is equal to the cross section area of the circular-cylindrical portion.
  • This bushing is also intended to be used only within the a.c. field. Electrically, it is built up in the same way as a conventional a.c. bushing with a condenser body made of oil-impregnated paper, bakelite paper or is impregnated with molded resin and has concentric layers of a conducting mate­rial.
  • the principle of the manufacture is that the transfor­mer side of the body is first wound into an inward conical shape into a diameter where about 70% of the stress lies, whereupon the body is continuously wound into an outward co­nical shape into the final outer diameter with 0% of the stress.
  • the advantage of such an embodiment is that a shor­ter bushing is obtained on the oil side.
  • the shield may be omitted.
  • Power transformers which are used in convertor plants entail special problems from the point of view of insulation, which somehow have to be overcome in order to ensure a satisfac­tory function.
  • each convertor In high voltage direct current plants, so-called HVDC plants, there is often used at least one convertor per pole and station. Normally, also, each convertor comprises seve­ral bridges connected in series. One of the poles of one bridge is normally connected to ground and the other pole is connected to the next bridge, and so on, thus obtaining the series connection. The direct voltage potential of each bridge relative to ground is then increased according to the number of bridges which are connected between the respective bridge and ground.
  • Each bridge in the series connection is supplied with an al­ternating voltage from a separate transformer.
  • the insulation on bushings and windings of the transformers which are connected to the bridges will also be subjected to an increasingly higher direct voltage potential with a superimposed alternating voltage.
  • the insulation of these must therefore be dimensioned so that they are capable of withstanding the increasingly higher electrical stresses to which they are then subjected.
  • the electric direct voltage field has a distribution diffe­rent from that of the alternating voltage field.
  • the distri­bution of the direct voltage is mainly determined by the re­sistivity of the various insulating mediums present in the field.
  • transformer oil, cellulose material and elec­tric porcelain are good electric insulators, a certain amount of electric current is flowing through these materi­als when subjected to an electric voltage.
  • the relation bet­ween the resistivity of cellulose material and transformer oil is about 100.
  • the transfor­mer bushing comprises a lower insulator.
  • a condenser type barrier is used which has internal cones which make contact, across a certain oil gap, with the outer conical part of the lower insulator of the bushing as well as with the conically formed insulation surrounding the conductor of the transformer.
  • the invention aims at designing a bushing of the above-men­tioned kind which withstand very high direct voltage stresses and enjoys relatively small outer dimensions.
  • the invention primarily relates to a transformer bushing with a condenser body for field control for transformers used in convertor plants.
  • the task of the condenser body is to overcome the flashovers which - as it has proved - may arise in transformer bushing termi­nals. It is designed so as to function as a barrier with both capacitive and resistive control of the electric field and is dimensioned so that the condenser body withstands the electric field strengths occurring in this bushing and in particular in the sensitive region at the connection between the conductor of the transformer and the bushing.
  • the conductor which comes from the trans­former winding and is to be connected to the conductor of the bushing is surrounded by a conducting tube which is co­vered by wound electrical insulation.
  • This insulation is formed, from the end of the conducting tube, as a straight frustrum of a cone with cross section areas with an increas­ing radius which than changes into a circular-cylindrical portion towards the transformer.
  • the conductor of the bush­ing also often consists of a conducting tube.
  • the part of the condenser body which is situated on the air side of the transformer bushing is formed as a conventional condenser body. This means that, counting from the fixing flange of the transformer bushing, it has a circular-cylind­rical portion which changes into an outwardlydirected straight frustrum of a cone with decreasing diameter. Also other embodiments of this portion may be used.
  • the part of the condenser body which is covered by the in­vention, i.e. on the oil side of the transformer bushing, normally counting from the fixing flange of the bushing, is formed as a circular-cylindrical portion the end of which is provided with an inwardly-directed straight frustrum of a cone.
  • the axial length of the circular-cylindrical portion which is located on the oil side of the bushing is largely adapted such that its end coincides with the transition from conical to circular-cylindrical portion of the insulation of the conductor coming from the transformer winding.
  • the coni­city of the cone, which from that point is directed inwards, largely coincides (see, however, below) with the conicity of the insulation of the conductor of the transformer winding with space for an intermediate oil gap.
  • Such a design of a condenser body means that a conventional condenser body is integrated with a condenser type barrier. This causes the electric field to be controlled in the de­sired way while at the same time obtaining a shielding of the conductor of the transformer. In this way the condenser body for the bushing according to the invention serves as an insulation barrier both for direct voltage and alternating voltage fields.
  • the condenser body for the bushing according to the invention is built up as a conventional condenser body, i.e. it consists of wound insulating material with condenser layers of foil type concentrically inserted therein.
  • the in­ner radius of the condenser body corresponds to the outer radius of the continuous current-carrying tube of the trans­former bushing.
  • the condenser body is manufactured from an insulating agent alternating with conducting layers to obtain the desired capacitive control of the electric alter­nating field.
  • the innermost condenser layer which is concen­tric with the conductor has an axial length which approxi­mately corresponds to the inner axial length of the conden­ser body. Outside of this innermost layer there are concen­tric layers alternating in length in the radial direction so that the stack formed by these layers tapers in either axial direction.
  • the taper is made so that, concurrently with in­creasing radius of the condenser body counting from the first layer, the layers are laid in an axial direction such that their outer edges connect with the outwardly-directed straight frustrum of a cone of the condenser body on the air side and an evenly decreasing taper counting from the inner­most layer towards the fixing flange on the oil side.
  • there are short layers which are laid such that, con­currently with increasing radius of the condenser body coun­ting from the innermost layer, they are laid in the axial direction such that their outer edges connect with the in­wardly-directed straight frustrum of a cone of the condenser body.
  • the axial length of these short layers is adapted such that their areas are constant, i.e. the axial length de­creases with increasing radius of the condenser body.
  • the innermost layer is connected to the central conducting tube, to which high vol­ tage is applied, and the outermost layer at the fixing flange is connected to ground.
  • the direct voltage field is controlled by several factors.
  • the medium that has the lowest resistivity is field-controlling.
  • an oil gap is formed between the insulator body of the conductor to the transformer winding and the surrounding inwardly directed straight frustrum of a cone of the conden­ser body. Since the oil has the lowest resistivity, most of the current is conducted in the oil gap, which therefore controls the field in parallel with surrounding surfaces. To obtain an even distribution of the field along these surfa­ces, it is therefore important that the width of the oil gap increases with decreasing radius. Otherwise, the field would be concentrated towards that part where the radius is smal­lest, i.e. where the cross section area of the oil gap is smallest.
  • the conicity of the inwardly directed straight frustrum of a cone of the condenser body and the conicity of the conical portion of the insulator body are suitably chosen such that the radial cross section area of the oil gap is approximately constant along the conical por­tion of the bodies.
  • Another field-controlling part is the radial distribution of the field in that part of the condenser body which does not contain any layers, i.e. around the innermost layer to which high voltage is applied.
  • the conducting layers function - in the direct voltage case - as equipotential plains which prevent the field from being concentrated to any part of the mentioned oil channel.
  • the condenser body is designed as a tight unit, for example impregnated and cured with some suitable cast compound.
  • the second alternative comprises enclosing the condenser body in a tight casing.
  • condenser body with the integrated con­denser type barrier in a transformer bushing according to the invention in relation to the concept with a separate condenser type barrier disclosed in US-A-539 209 is that the outer dimensions of the system can be made smaller. Another advantage is that the extent of the interfaces which are subjected to a tangentially directed electric field strength is reduced.
  • the proportions bet­ween the diameter and axial length of the condenser body are not according to scale. The same is true also of the coni­city of the cones.
  • the principal embodiment where the condenser body is formed as a tight cast unit is shown in Figure 1.
  • the condenser body 1 is built up as a solid of re­volution which consists of wound insulating material with concentrically inserted foil-type condenser layer.
  • Figure 1 also shows the central current-car­rying part 2, in the form of a tube, of a transformer bush­ing around which the condenser body 1 is centered, as well as the conductor of the transformer consisting of an inner energized tube 3 and insulating material 4 wound thereon, which material 4 is formed as a circular-cylindrical part 6 which changes into a conical taper 5 towards the end of the tube.
  • a transformer bushing in which the condenser body is to be included normally has an upper insulator of electric porce­lain acting towards the air side.
  • On the oil side transfor­mer bushings normally also have a lower insulator of, for example, electric porcelain.
  • the condenser body in the first alternative is impregnated with a suitable cast compound, for example epoxy.
  • a suitable cast compound for example epoxy.
  • the con­denser body is then wound from, for example, an insulation paper which is impregnable by the cast compound used.
  • the condenser body On the air side the condenser body is formed as a condenser body according to the state of the art, i.e. with a circu­lar-cylindrical portion 7 which changes into an outwardly-­directed straight frustrum of a cone 8.
  • the condenser body On the oil side the condenser body continues in a circular-cylindrical portion 9 with the same outside diameter as the circular-cylindrical portion on the air side.
  • the axial length of the outer con­tour of the circular-cylindrical portion is adapted such that its end coincides with the transition of the insulation from the conical to the circular-cylindrical portion of the conductor of the transformer winding.
  • the first and innermost condenser layer 11 is electrically connected to the current-carrying tube 2 of the bushing, as indicated at the point of connection 12.
  • This first layer has an axial length which corresponds to the inner axial length of the condenser body. It is surrounded by concentric layers 13 which are laid one above the other in a radial di­rection and tapering relative to the first layer, in an axial direction. The taper is done by laying the layers, concur­rently with increasing radius, in an axial direction so that the outer edges on one side connect with the conical contour of the air side and with an evenly decreasing taper towards the fixing flange of the transformer bushing on the other side. The outermost of these layers is connected to ground potential.
  • the condenser body is provided with concentric short layers 14 which connect with the contour of the in­wardly directed straight frustrum of a cone.
  • the axial length of these short layers is adapted so as to have a practically constant area independently of the radius on which they are situated.
  • FIG. 2 An embodiment of a condenser body according to the above-­mentioned second alternative is shown in Figure 2.
  • the field-controlling parts of the condenser body i.e. the wound insulating material and the layers, are arranged, from the design point of view, in the same way as in Figure 1.
  • the insulation part consists, for example, of oil-impregnated insulation paper.
  • the entire condenser body is surrounded by oil enclosed in a tight casing 15. This leads to the creation of two oil gaps between the inwardly directed cone of the con­denser body and the conical portion of the conductor of the transformer winding. i.e. inside and outside the tight ca­sing, respectively.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Insulators (AREA)
  • Housings And Mounting Of Transformers (AREA)
  • Transformers For Measuring Instruments (AREA)
EP19900120182 1989-10-31 1990-10-20 Buchse für hohe Gleichspannungen Revoked EP0429843B1 (de)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE8903633 1989-10-31
SE8903633A SE464898B (sv) 1989-10-31 1989-10-31 Kondensatorkropp foer faeltstyrning av en transformatorgenomfoerings anslutning till en transformatorlindnings uppledare hos stroemriktartransformatorer

Publications (2)

Publication Number Publication Date
EP0429843A1 true EP0429843A1 (de) 1991-06-05
EP0429843B1 EP0429843B1 (de) 1995-12-20

Family

ID=20377340

Family Applications (1)

Application Number Title Priority Date Filing Date
EP19900120182 Revoked EP0429843B1 (de) 1989-10-31 1990-10-20 Buchse für hohe Gleichspannungen

Country Status (7)

Country Link
EP (1) EP0429843B1 (de)
JP (1) JPH03180011A (de)
BR (1) BR9005510A (de)
CA (1) CA2028987A1 (de)
DE (1) DE69024335T2 (de)
DK (1) DK0429843T3 (de)
SE (1) SE464898B (de)

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007107492A1 (de) * 2006-03-21 2007-09-27 Siemens Aktiengesellschaft Verbindungselement für eine elektrische abschirmungsanordnung
WO2008027007A1 (en) * 2006-08-31 2008-03-06 Abb Research Ltd High voltage dc bushing and device comprising such high voltage bushing
US8802993B2 (en) 2006-08-31 2014-08-12 Abb Research Ltd. High voltage bushing
WO2015140208A1 (en) * 2014-03-19 2015-09-24 Abb Technology Ltd Electrical insulation system and high voltage electromagnetic induction device comprising the same
EP3358690A1 (de) * 2017-02-07 2018-08-08 NKT GmbH & Co. KG Verbindungsmuffe
DE102018116416A1 (de) * 2018-07-06 2020-01-09 Nkt Gmbh & Co. Kg Verbindungsmuffe

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102006008922B4 (de) * 2006-02-21 2009-01-02 Siemens Ag Elektrische Abschirmanordnung
DE102010063979A1 (de) 2010-12-22 2012-06-28 Siemens Aktiengesellschaft Elektrische Abschirmanordnung einer Trennstelle einer Leitungsführung für eine HGÜ-Komponente
DE102012203709B4 (de) * 2012-03-08 2024-04-04 Siemens Energy Global GmbH & Co. KG Hochspannungsdurchführung für Gleichspannung
DE102018215274A1 (de) * 2018-09-07 2020-03-12 Siemens Aktiengesellschaft Anordnung und Verfahren zur Potentialabsteuerung in der Hochspannungstechnik

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH506165A (de) * 1968-12-11 1971-04-15 Hitachi Ltd Kondensator-Durchführungsisolator

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH506165A (de) * 1968-12-11 1971-04-15 Hitachi Ltd Kondensator-Durchführungsisolator

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007107492A1 (de) * 2006-03-21 2007-09-27 Siemens Aktiengesellschaft Verbindungselement für eine elektrische abschirmungsanordnung
WO2008027007A1 (en) * 2006-08-31 2008-03-06 Abb Research Ltd High voltage dc bushing and device comprising such high voltage bushing
US8088996B2 (en) 2006-08-31 2012-01-03 Abb Research Ltd. High voltage DC bushing and device comprising such high voltage bushing
US8802993B2 (en) 2006-08-31 2014-08-12 Abb Research Ltd. High voltage bushing
WO2015140208A1 (en) * 2014-03-19 2015-09-24 Abb Technology Ltd Electrical insulation system and high voltage electromagnetic induction device comprising the same
EP3358690A1 (de) * 2017-02-07 2018-08-08 NKT GmbH & Co. KG Verbindungsmuffe
DE102018116416A1 (de) * 2018-07-06 2020-01-09 Nkt Gmbh & Co. Kg Verbindungsmuffe
US11502499B2 (en) 2018-07-06 2022-11-15 Nkt Gmbh & Co. Kg Coupling sleeve

Also Published As

Publication number Publication date
CA2028987A1 (en) 1991-05-01
JPH03180011A (ja) 1991-08-06
SE8903633D0 (sv) 1989-10-31
DE69024335D1 (de) 1996-02-01
BR9005510A (pt) 1991-09-17
DK0429843T3 (da) 1996-05-06
SE8903633L (sv) 1991-05-01
SE464898B (sv) 1991-06-24
EP0429843B1 (de) 1995-12-20
DE69024335T2 (de) 1996-08-14

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